This invention pertains to improving the decoupling efficiency and sensitivity of nuclear magnetic double resonance experiments by means of a novel saddle coil arrangement analogous to the capacitively shortened slotted line resonator. Heretofore, capacitively shortened slotted line resonators have been described by Schneider and Dullenkopf (Rev. Sci. Instr., 1977), Hoult (Prog. in NMR Spect., 1978), and Doty (Doct. Diss., 1983). Similar resonators are in wide-spread useage for high field .sup.1 H, .sup.3 H, and .sup.19 F decoupling and observation. More recently, they have been applied to imaging of large objects at lower fields. They are sometimes called single turn saddle coils, and sometimes are referred to as decoupling coils. These resonators are often double tuned, by means of additional coils, to a second resonant frequency. A more detailed analysis of double tuned circuits for NMR signal reception may be found in the references.
The resonator will be referred to as a single-turn resonator where n in the following equation is approximately equal to unity. EQU V.perspectiveto.n.intg.d.phi..sub..perp. /dt
where V is the magnitude of the largest voltage induced anywhere in the circuit by the time dependent normal magnetic flux, d.phi..sub..perp. /dt, linking the loops.